The Triangles of Mrs Williams
by hennyboo13
Summary: Following summer adventures at the Mystery Shack, Dipper and Mabel are back in school. Now that they are in seventh grade, they must deal with learning new, boring topics, even though they had learned about cooler stuff during their summer adventures. However, little do they know, their Geometry Teacher Mrs. Williams has a dark secret, and she wants something valuable from them.
1. Chapter 1

Dipper opened his eyes and looked around the room. Seeing that it was morning, he looked at the clock on the nightstand to see that it was 7:45 AM. He got up and climbed to the top bunk to wake up his sister. "Mabel, get up!" he said as he shook her shoulder. "Get up, it's Monday!"

Mabel blearily lifted her eyes. Yawning, she rolled over to look Dipper in the eye. "Morning bro." she said as she got up and climbed down the stairs to start getting ready for school. "I hate normal days" she groaned as she put on a black sweater with a mouth sticking it's tongue out. Both of them had not yet gotten used to being at school again, as this was one month into seventh grade, and they were still used to strange things happening every day back at Stan's place in Gravity Falls.

The two rushed downstairs to find that their mother had just left for work and their father hadn't gotten up yet. Walking into the kitchen, Dipper took out two eggs and two strips of microwavable bacon. He lit the stove and cracked the eggs into a skillet, but before he could place the bacon in the microwave, Mabel stopped him.

"Dipper! Don't!" she shouted, slapping the bacon out of his hands. Dipper knew what Mabel meant, and he was sick of it.

"For the billionth time, this isn't Waddles!" he convinced her. "Soos is taking care of him, don't you remember?"

"I'm still worried!" said Mabel, "I can't bear to see someone eat Bacon without thinking of Waddles getting hurt!"

"Ok, whatever, sis." Dipper put the bacon back in the fridge. "We'll split the eggs."

"Thank you!" Mabel put one of those big smiles on her face which showed every one of her braces. When the eggs were fried, they put them down on the table and ate breakfast.

Dipper packed his homework in his backpack. Mabel saw this and then told him, "I don't think Mr. Deutscher will give you a good grade on your homework."

"But witches do exist! It's in the book!" he tried to convince her, but Mabel didn't think it was a good idea. She had to lie on her homework, as she made what the teacher would think of as the right answer, covering up the truth about what really happened that fateful summer in Salem back in 1692.

As they were finishing up their breakfast, they heard some growling upstairs. Both Dipper and mabel's eyes widened as they looked up at the ceiling to hear slow, heavy footsteps that caused the wooden floorboards to creak, as if they were back at the Mystery Shack and there was a monster lurking around upstairs.

"Oh no!" yelled Dipper in a panic, "Dad hasn't had his coffee yet!"

The twins quickly put on their backpacks and raincoats, and as they heard the heavy footsteps walking down the stairs, they tried not to look behind them.

Right as dad was about to reach the bottom of the stairs, Dipper and Mabel rushed out the door and started running down the street into the rain. They eventually stopped at the payphone where the school bus would pick them up.

"Dipper?" asked Mabel.

"Yeah?" Dipper replied.

"Are you worried that a monster is going to pop out of the bushes?" she looked into the deciduous woods across the street.

"Relax, sis." he said as he put his hand on her shoulder, trying to comfort her. "I am aware you're still used to our summer adventures. Now we're back at home in California, waiting in the rain for the school bus to arrive, and nothing strange is going to happen."

"Still, I get worried about things. Sometimes I worry about if Grunkle Stan's alright."

"Mabel, he's going to be just fine. Believe me." As he was saying this, Mabel noticed two lights behind the heavy rain that seemed to be getting closer and closer. Were they monster eyes? Nope. It was just the bus. She sighed in relief.

The doors opened. "Oh look, it's Bipper and Maple!" said the bus driver, who, for some reason, looked like a female version of Soos. They got on the bus and walked down an aisle full of noisy children. They sat down at a seat in the very back of the bus, across the aisle from Fregly, a boy who Mabel swore was like a younger version of Mr. McGucket.

"Aw man," Dipper said in disappointment, "taking the bus to school reminds me of taking the bus up to Gravity Falls."

"Me too, I miss our adventures there." Mabel told him, and then she looked out the window of the bus to see a sign showing how many miles it was to the Oregon border on I-5. This made her a bit upset, but she got even more unhappy when she saw a large billboard on the side of the highway advertising the Mystery Shack, showing Grunkle Stan spreading his arms out wide, as if to hug them. Dipper noticed this too, and they both began to tear up without having a single question on why Stan would advertise his tourist trap hundreds of miles south. "I miss the Mystery Shack." cried Mabel as she hugged her brother. "I can't handle to wait until next summer."

"Well, don't get too sad." Dipper unzipped his backpack. "I got something that can remind us of last summer and look forward to next summer." Mabel was shocked to see that he had been carrying all three of the books in his backpack.

"What? How'd you get those?" she asked in surprise.

"Grunks gave them to me before he left. He thought it would be in safer hands if I kept it for the school year?"

"That's not a very wise move." Mabel was starting to get a little worried on what would happen to the books. "Isn't it dangerous to keep those with you? Someone might try to steal them and use them against us."

"Relax, we've defeated Bill three times already, Gideon's in prison, and I doubt any culture or organization is after it."

"Still, I'm kind of scared that Bill will come back."

"Why?"

"Because our geometry teacher is obsessed with teaching triangles in geometry!"

Dipper hadn't noticed this before, and he felt kind of stupid that it took a month before Mabel could point it out to him. He knew that Mrs. Williams, their geometry teacher, was obsessed with triangles. Dipper and Mabel would notice triangles everywhere in her math class, on the board, on the homework, and even on her coffee mug. Although she was a big jerk to everyone, Dipper had noticed that she was the meanest to him and Mabel. All the students hated her. Whenever a student did bad on homework or a quiz, she would angrily throw it down on the floor and yell, "I could teach my dog to do better than this!"

As Dipper continued to think about a connection between Mrs. Williams and Bill Cipher, the bus pulled in at the school parking lot. Everyone got off and walked through the main entrance into the long and wide school hallway.

Dipper and Mabel opened their lockers. "Now remember" said Mabel, "Keep those books in your backpack and make sure your locker is locked. I don't want something bad to happen to them."

"Alright, I'll do it for you." Dipper took out his notebook, homework folder, and history textbook before he zipped up his backpack and closed his locker. Then they walked to Mr. Deutscher's social studies class, unaware of the witch-like geometry teacher watching them from the window of the door to her classroom.


	2. Chapter 2

"I swear!" said Dipper in an attempt to convince his teacher, "Witches are real! Those people accused of sorcery in the Salem Trials of 1692 really were guilty!"

"Stop trying to be cool" said Mr. Deutscher. "This is history class, not Magick and Monsters. What you are saying is false, and the accusers were crazier than the accused. You may sit back down, Douglas."

Dipper sat back down next to Mabel and lay his head on the desk. He started reading his social studies textbook in order to reread the "Correct" information on the Salem Witch Trials and take notes in order to get the credit for the homework he got a zero in.

Just then, Bess McKinley raised her hand. "Yes?" asked Mr. Deutscher.

"Teacher, I think he may be saying that because he thinks Mrs. Williams is a witch, just like everyone else in her math class!" she said.

Mr. Deutscher gave Dipper a dirty look. "Is that so?"

"No, Mr. Deutscher, she was just misinterpreting things!" Dipper didn't really know what to say, as Mabel had told him not to mention the book to anyone but her.

"Come with me" said Deutscher, and he grabbed Dipper out of his seat and walked him out the door to the Vice Principal's office.

Although Mabel was worried about what would happen to him at first, Dipper was back at second period English with Mr. Gillespie, who was a big jerk. While Mrs. Williams was definitely evil, Mr. Gillespie was just a plain jerk.

Abadeer quickly stood up from his desk after all the students had taken a seat down. "All right class" he spoke loudly, "hand in your reading logs for this weekend's assigned chapter of Lord of the Flies."

Mabel's eyes widened. "Uh oh" she muttered to Dipper, "I didn't read that chapter."

Dipper knew why she didn't read it. "Mabel, I know it makes sense why you won't read it, but you can't literally judge a book by its cover."

"But the severed head on the cover looks too much like Waddles!" she held the book up to Dipper to show him the bloody severed pig head as the cover art. He didn't mind the cover and was eager to read it, but it made sense that his sister wouldn't want to read a book about a pig getting killed.

All the students except Mabel put their reading logs on Mr. Gillespie's desk, but he didn't seem to notice. "Alright class, now who would like to dis-" he was interrupted by a smacking, sloshing, chewing noise in the room, and he could tell who it was. "Mabel Pines, are you chewing on bubble gum?"

"Yes it is!" Mabel stretched the gum out of her mouth.

"Then take it out of your mouth and place it on the end of your nose!"

For the rest of the class, Mabel felt humiliated because everyone could see a wet, pink blob on her nose, but she had to obey the teacher.

"Well, it's time to review!" said Mr. Gillespie. "Now, what is the name of the fair-haired boy, and what is the name of the fatboy?" he decided to pick a random kid in the audience. Noticing Dipper, he asked, "Douglas? How about you?"

Dipper stood up. "Ralph is the boy referred to as the boy with fair hair, while the fatboy's nickname is Piggy." as Dipper was answering, Mabel noticed Mrs. Williams peering through the door window. Raising her hand up, Mrs. Williams levitated the screws out of Dipper's desk, falling on the floor without making a sound. When Dipper sat down, the desk fell apart. "OW!" he shouted. Mr. Gillespie wasn't too happy with this.

"ALL RIGHT!" he terrifyingly yelled, "WHO HERE REMOVED THE SCREWS FROM DOUGLAS'S DESK?!" he walked up to Mabel, who was sitting next to Dipper. "Who took the screws?" he asked. Mabel knew the answer, but she knew he wouldn't believe her.

"Um... I think it was... well..."

Tired of Mabel's hesitation, Mr. Gillespie grabbed her by the collar of her sweater. "I SAID, WHO TOOK THE SCREWS?!"

"It was... It was..." she remembered the girl who had gotten Dipper in trouble, and she wanted to get her revenge on her. "It was Bess McKinley!" she said, pointing to Bess.

"What? What do you mean?" she asked in shock and confusion, "It wasn't me, I swear! I didn't take the screws from Dipper's desk!"

"Yeah, right" said Mr. Gillespie, and he grabbed Bess by the arm and dragged her out of the room. The rest of the class wasn't surprised, as he did this to kids at least twice a week.

Following English class, it was time for third period: Geometry with Mrs. Williams. Dipper and Mabel slowly walked into her classroom, and she stood next to the door to greet the students. When the two walked in, Mrs. Williams said, "Well hello, you two twins." she noticed Mabel's sweater, which made her mad. "Take off your sweater!" she shouted, "Rock and Roll is evil, and it will ruin your brain!"

Mabel was confused by this. "But Mrs. Williams, how is my sweater related to rock music? It's just a floating mouth sticking it's tongue out." of course, when clothes shopping, her mother always chose her sweaters, so it was common for Mabel to not understand the pop culture references on them.

"Excuses, excuses, take it off!" scolded Mrs. Williams, and Mabel obliged, now only left in a white tank top. She grabbed her sweater and ripped it in half with her bare hands.

"And why are you saying Rock and Roll is evil?" Mabel asked again. "Are you still stuck in 1958? Because everyone lis-"

Mrs. Williams grabbed Mabel by the straps of her tank top. She could smell the hag's extremely smelly breath. Did she eat a dead rat or something? "Don't try to out-smart me! Now sit down and engage in the class!"

Dipper and Mabel took out their homework and placed it on the teacher's desk. The homework, or course, was all about the vertexes of triangles. There was never once a day where there would not be at least one triangle discussed in her lessons.

"Today class," said Mrs. Williams, "we are going to start discussing 3-D shapes. As an introduction to this, here is an example of a 3-D shape." she drew a pyramid on the blackboard. Another thing to note was that she was the only teacher to use a blackboard rather than a dry-erase board.

Dipper knew that it was finally time for him to question on why she was so obsessed with making her students learn about triangles. He raised his hand. "Mrs. Williams?"

"Yes, Dipper?" she replied. This shocked him, as none of the other teachers would call him by the name he preferred, as they would always mention him by his real name. In fact, this was the first time Mrs. Williams had mentioned his name.

"Why are you so obsessed with triangles? And second, why are you the meanest to Mabel and I?"

Mrs. Williams suddenly froze for a second before she strictly said, "Dipper. Mabel. See me after class ends."

The two couldn't concentrate for the rest of class. They wondered about why she wanted to meet with them after class was over, and they were impatient to find out. After the class was dismissed, Dipper and Mabel stayed behind, ready to hear Mrs. Williams yell at them for fifteen minutes and tell them not to criticize her lessons.

"You two" said Mrs. Williams, walking up to their desks. "I see you've finally come to question why I'm so obsessed with triangles. Now I demand something from you." she reached her hand out to Dipper. "Give me the books."

Both Dipper and Mabel were shocked. Mabel looked at him in a way to tell him "See? I told you!"  
"What?! How do you know? Why do you know I have the three books?" Dipper asked in confusion, surprised. "And why do you want it?"

"Do you know what is short for William?" asked Mrs. Williams, grabbing her long, crooked nose.

It took Dipper a moment to think about it until he made a realization about his geometry teacher. "Wait a minute! William is short for-" just as he was about to say what the name was short for, Mrs. Williams pulled her nose, which pulled off her entire face with it.

"AHAHAHAHAHAHAHAHAHA!"

Dipper and Mabel screamed in terror as they looked into the eye of Bill.


	3. Chapter 3

"AHAHAHAHAHAHAHAHAHA!" Laughed Bill, clutching Mrs. Williams's face in his "hand". Dipper and Mabel were both taken by surprise. Even though Dipper had already made a sort of connection between Bill and Mrs. Williams, he didn't know that she was really Bill in disguise going after them.

Mabel was especially shocked. "Bill Cipher?! But.. But..."

"Yes, it's me!" Bill dropped Mrs. Williams's fake body, leaving him as the floating triangle he was. "You knew I'd get my revenge on you two someday, Dipper!"

"Well, how'd you track us down like that?" Dipper asked. "How do you know where we live and go to school and everything!"

"I took a little valuable something of yours when I took over your body!" Bill held up Dipper's Santa Barbara Elementary School ID Card. "And whaddaya know, now I know your real name is Douglas!"

"I prefer not to be called that."

"Whatever you say, kid. Now let's get back to business. GIVE ME THOSE BOOKS!" Bill turned orange to show increasing demand.

"No, I'm never going to let you have the journal of Stanley Pines! And you'll never find out where it is either!"

"Well I know you have it! Now I'm going to find it!" Bill quickly floated out the door of the classroom and darted down the hallway.

"C'mon Mabel, we have to stop him!" Dipper and Mabel ran after him. "He set up the ultimate trap for us! Now he's gonna find the books and we're doomed!"

"Well, I must admit, the mask thing was kinda cool." Mabel pointed out.

The two kept their eyes on the floating yellow triangle as they ran through the school hallway and down the staircase. They knew it would be easy for him to find the books, as all of the lockers had the students' names on them.

When they finally reached Dipper's locker, it was still closed and locked, and Bill wasn't there. "Good" said Dipper in relief, "he hasn't found it yet." he turned the wheel on the lock of his locker door and opened his locker. "Well, I guess I better- WHAT?" Dipper's backpack was open and the books were gone.

"Don't you remember?" said Mabel behind him, looking down. "Bill can pass through solids. It's too late"

"No it's not!" Dipper convinced her. "We will find the books and defeat Bill! He could be anywhere?" just then, someone tapped his shoulder. He looked behind him to see Bill carrying the books down the hallway. "That way!"

Bill tried to find a way out of the school in order to escape the two kids and finally keep the books forever. They chased him downstairs to the lower level, where he stopped at double doors which he assumed was the exit to give his final speech to them before he left. "You're too late!" he boasted. "These books are MINE! With these three books, I will unleash the power that lay inside them!"

Mabel realized what time it was. "Hey Bill, do you know what those doors lead to? The cafeteria. Do you know what time lunch ends?" Mabel pointed to the clock above the doors.

Bill saw that it was exactly 12:59:59 PM. A second later, a long, loud, and low buzz came on the loudspeakers in the hallway, and immediately he was crushed under the feet of hundreds of kids.

"Recess!" shouted Mabel as the crowd of children trampled Bill beneath their feet.

"Hey! Ow! Stop it! Ack!" he said as he kept getting stepped on. When all the kids had left the hall for the school playground, Bill lay flat on his face. However, the books were gone.

"Oh no!" said Dipper, noticing this. "Where did the books go?" he looked around trying to find them. They could have been crushed by the crowd, and that would be a huge problem for both Bill and the twins.

"Over here!" said Mabel, pointing to two of the books on the floor a few meters down the hall. As they ran up to it, they were unaware that Bill had gotten back up.

"You found them!" Dipper told Mabel. "But where is the third one."

"Looking for something?" said Bill behind them. The two turned to see that he had one of the books. "Now I demand the other two. Gimme!" Bill started to chase them again.

"We won't let Bill get away with his evil plan!" said Dipper as he ran. "We'll have to think of a way to get the one he has!"

Mabel took emphasis on the word "Evil". She thought about the last time she'd heard that word used to describe something. No, it wasn't his plan, it was what Bill described the logo on her sweater to be, and she now realized one of his weak points. She stopped and faced Bill. "Hey Billy Goat!" she shouted, "Listen to some of this!" she threw an iPod at him.

Bill recognized the music that was playing. "Wait, what is that? Is it? Oh no, its..." he saw the name of the song playing: I Love Rock n' Roll, by Joan Jett. "Noooo! I HATE Rock n' Roll! It's EVIL! STAAAAAHP!"

Dipper and Mabel watched as Bill began to light up bright from listening to the "Evil" music. Then, in a big, bright burst, he was gone, disappeared back into his own dimension. The third book lay on the floor, and Dipper picked it up.

"We did it!" cheered Mabel, and the two high-fived. They had defeated Bill once again, and even though they were unsure on whether he would get his revenge again, the books were at least in safe hands... for now.

It was now Monday evening after dinner, and Dipper and Mabel had just finished their homework. Mabel was web surfing on his computer, as she'd already spent an entire summer without any internet, but that was alright, since she had a lot more fun than being on the internet at Gravity Falls.

"Aw man, Mabel's Little friend has died!" she cried, as she hadn't logged into Net Kritterz all summer. "But at least I've got a real friend."  
"Waddles?" asked Dipper.

"No, even better" said Mabel, wrapping her arms around him and giving him a hug. "You. I had such a good time having another adventure today."

"I sure did too."

Just then, Dipper and Mabel's shared computer had an incoming skype call from "MrMystery1938". Dipper rushed to answer the call, as he knew exactly who it was. When he pressed the space key, Grunkle Stan's face popped up on the screen. "Hello there kids!"

"Grunkle Stan!" Dipper and Mabel cheered simultaneously.

"Look, I finally got a new computer!" said Stan. "Lisa finally broke down after thirty years. So I sold it off and said it worked so I could buy a new one! So how are you two? You keepin' a good watch on them books?"

"Sure we did!" Dipper gave Mabel a wink. "We'll make sure nothing happens to 'em!"

Stan turned the computer camera to face Wendy. "Yo Dipper" she said, "How's it going?"

"Is Soos there too?" Mabel asked, just as Soos walked by the camera and noticed the skype call. "Hey Soos, it's us!"  
"Stan trapped you two in a computer? Get them out!"

"Calm down Soos, it's just a webcam call." Stan told him.

"I can't wait to see you guys this summer!" cheered Mabel. "And I can't wait to see Waddles too!"

"Oh yeah, look who else says hello!" Soos lifted up Waddles so Mabel could see. When he saw her, he squealed in excitement.

"Hello Waddles! I miss you!"

"I am sure he can't wait to see you this summer, too" said Stan. "And we've just called you to say we miss you, and we're looking forward to seeing you this summer."  
"We sure are too" Dipper told them. "And we'll make sure nothing happens to these books. Goodbye!"

"Goodbye!" said Stan, Wendy, and Soos all at the same time. And then, they disconnected.

"Well, that was nice" said Dipper. "Great to know they miss us too."

"I can't wait for summer" Mabel told him. "Hey, we've finished our homework. You wanna play another round?"

"Sure!" he said, and then they went downstairs to the dining room table to play Magick and Monsters.


End file.
